Piston tool buffer assembly

Abstract

A buffer assembly for use in a piston-type powder-actuated tool, which buffer assembly provides for a longer useful life of the piston. The buffer assembly includes an elastomeric member which is disposed in the bore of the tool barrel, and which is fitted with a metallic cap. The tool barrel and metallic cap combine to control and constrain radial and longitudinal expansion of the elastomeric member, when the latter is impacted by the driven piston. In this manner, extrusion of the elastomeric member is prevented and, at the same time, the piston is prevented from contacting other hardened tool surfaces.

What is claimed is: 
     
       1. In combination a piston buffer assembly and a powder-actuated piston-type fastener driving tool said tool having a barrel with a bore and a piston reciprocally slidably mounted in said barrel bore, said buffer assembly comprising: (a) an annular elastomeric member disposed in said tool in a muzzleward area thereof, said elastomeric member having a bore through which a stem part of said piston extends;   (b) first means in said barrel radially and axially closely confining a muzzleward end portion of said elastomeric member;   (c) second means in said barrel closely radially confining a breechward end portion of said elastomeric member, said means allowing axial expansion of said member in a breechward direction;   (d) means for permitting a portion of said piston having a larger diameter than said stem part to enter said bore of said elastomeric member when said piston is driven in said tool whereby said elastomeric member expands only axially in a breechward direction; and   (e) fixed means in said barrel bore for limiting the extent of breechward expansion of said elastomeric member.   
     
     
       2. In combination a piston buffer assembly and a powder-actuated piston-type fastener driving tool said tool having a barrel with a bore and a piston reciprocally slidably mounted in said barrel bore, said buffer assembly comprising: (a) an annular elastomeric member disposed in said tool in a muzzleward area thereof, said elastomeric member having a bore through which a stem part of said piston extends;   (b) means closely radially confining said elastomeric member to substantially limit radial expansion thereof when said elastomeric member is impacted by said piston, said means further being operable to cause said elastomeric member to expand axially in a breechward direction when said elastomeric member is impacted by said piston; and   (c) fixed means in said barrel bore for limiting breechward expansion of said elastomeric member when the latter is impacted by said piston to temporarily render said elastomeric member substantially non-compressible.   
     
     
       3. A piston buffer assembly for use in a powder-actuated piston-type fastener driving tool, said buffer assembly comprising: (a) an annular elastomeric member having a bore which extends axially therethrough and having an outer side wall and opposed end walls;   (b) a metallic cap mounted on said elastomeric member, said cap extending axially over and closely confining at least a portion of said outer side wall of said elastomeric member, and said cap having an opening at one end thereof, said opening having a diameter which is larger than the diameter of said bore through said elastomeric member; and said cap including a radially inwardly extending end wall part at said one end of said cap, said end wall part forming said opening in said cap, and said end wall part overlying and closely confining a portion of a corresponding one of said end walls of said elastomeric member.   
     
     
       4. In combination with a powder-actuated piston-type fastener driving tool of the type having a barrel with a bore in which there is reciprocally slidably disposed a fastener driving piston, and having a muzzle bushing member secured to said barrel, a piston buffer assembly comprising: an annular elastomeric member disposed in said barrel bore, said elastomeric member having an axial through bore through which a stem portion of said piston extends; means in said muzzle bushing for axially and radially outwardly closely confining a muzzleward end portion of said elastomeric member; a metallic cap member mounted on a breechward end portion of said elastomeric member, said metallic cap member radially outwardly closely confining said breechward end portion of said elastomeric member; a breechward end wall of said elastomeric member being exposed for impact by a dimensionally expanding surface of said piston stem when said piston is propelled muzzleward through said barrel bore to drive a fastener whereby said elastomeric member will expand axially in a breechward direction upon being impacted by said piston surface; and means in said barrel bore to engage said cap member for limiting the extent of axial expansion of said elastomeric body. 
     
     
       5. The tool and piston buffer assembly of claim 4, wherein said cap includes a radially inwardly directed flange overlying an outermost part of said breechward end wall of said elastomeric member.